20. • A straight, horizontal segment of wire carries a current in the +x-direction in a magnetic field that is directed in the −z-direction.

(a) Is the magnetic force on the wire directed in the (1) −x−, (2) +z−, (3) +y−, or

(4) −y-direction? Explain.

(b) If the wire is 1.0 m long and carries a current of 5.0 A and the magnetic field is 0.30 T, what is the magnitude of the force on the wire?